tests: un-skip sweep — 26 tests revived on the JSPI build, failures re-gated with fresh evidence

Empirical pass over every skip/fixme whose premise the JSPI migration
could have changed. Revived (verified green):

- Firefox wasm-budget guards RETIRED (drift-trio, drift-trio-fuzz,
  drift-trio-scenarios, ysync-two-tab, ysync-libsymbols): the JSPI
  build (~half the asyncify size) fits three editor tabs inside
  Firefox 153's per-process budget — +20 firefox collab tests.
- roundtrip 'pcbnew preserves items through a yjs round trip': the
  asyncify-fragile envelope parse it waited on is gone — both engines.
- drift-trio-scenarios S4/S4b: converge now (was KNOWN ~5-8%).
- pcbnew-collab + eeschema-collab 'a local move propagates A→B'.
- web eeschema-fp-selector, read-only-editor's fixme'd writer-stream
  test, footprint-browse-remote read path (chromium; firefox gated:
  FootprintEnumerate rows never appear in 60s — slow wasm tier
  suspected).

Still broken, re-gated with re-verified reasons:

- 3d-viewer raytracer engine toggle: still inert, both engines.
- maximize display geometry: wxDisplay reports 0x0 in the harness.
- web editor WRITE bridge (symbol/footprint × remote/spike): wedges at
  the New Symbol/Footprint dialog step on both engines — the
  web-e2e-rot 01 gap stands for writes.

Verify runs: kicad+wx touched files 93 passed / 0 failed / 7 skipped
(intended gates); web touched files 7 passed / 0 failed / 9 skipped.
lint:determinism + lint:ci-coverage green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016X9eh1s5sTx1o9Em9KBuwR

tests/kicad/pcbnew-collab.spec.ts

@@ -437,7 +437,8 @@ test.describe("pcbnew collab bridge — single page", () => {
 test.describe("pcbnew collab bridge — two tabs (BroadcastChannel)", () => {
   // SKIP headless for the same reason as the single-page apply test (harness can't PAINT).
   // Verified working in the real web app.
-  test.skip("a local move propagates A→B", async ({ context, testLogger }) => {
+  // re-enabled 2026-08-13: passes on the JSPI build (both engines)
+  test("a local move propagates A→B", async ({ context, testLogger }) => {
     const channel = `pcb-collab-e2e-${test.info().workerIndex}`;
     const bundle = path.resolve(__dirname, "../apps/kicad/collab-bundle.js");